Peroxymonosulfate compositions containing acylate oxidation promoters,and their use

ABSTRACT

PARTICULATE COMPOSITIONS COMPRISING ADMIXTURES OF A WATER-SOLUBLE PEROXYMONOSULFATE AND A WATER-SOLUBLE SALT OF A 1 TO 4 CARBON SATURAED ALIPHATIC MONOCARBOXYLICACID AS AN OXIDATION PROMOTER; ALSO, AQUEOUS COMPOSITIONS WHICH ARE SOLUTONS OF SUCH A PEROXYMONOSULFATE HAVING A PH OF 5 TO 10 AND CONTAINING THE ACYLATE ANION OF SUCH AN ACID. SUCH SOLUTIONS ARE USEFUL FOR OXIDATIVE PURPOSES SUCH AS THE BLEACHING OF TEXTILES WHICH ARE AMENABLE TO BLEACHING WITH PEROXYMONOSULFATE, AND THE REMOVAL OF STAINS THEREFROM. THE PREFERRED PEROXYMONOSULFATE IS THE TRIPLE SALT OF POTASSIUM PEROXYMONOSULFATE OF THE FORMULA KHSO4.52SO4.2KHSO5. THE PRFERRED PROMOTERS ARE THE ALKALI METAL ACETATES, E.G., SODIUM ACETATE. THE PREFERRED PARTICULATE COMPOSITIONS ARE SUBSTANTIALLY ANHYDROUS ADMIXTURES OF THE ABOVE POTASSIUM PEROXYMONOSULFATE, SODIUM ACETATE, A BUFFERING AGENT SUCH AS TRISODIUM PHOSPHATE OR TETRASODIUM PYROPHOSPHATE, AND A SOLID DESICATING AGENT, PREFERABLY ANHYDROUS MAGNESIUM SULFATE.

Patented Jan. 19, 1971 3,556,711 PEROXYMONOSULFATE COMPOSITIONS CON-TAINING ACYLATE OXIDATION PROMOTERS,

AND THEIR USE Neil J. Stalter, Wilmington, Del., assignor to E. I. duPont de Nemours and Company, Wilmington, Del., a corporation of DelawareNo Drawing. Continuation-impart of application Ser. No. 691,952, Dec.20, 1967. This application June 16, 1969, Ser. No. 833,697

Int. Cl. D061 3/02 US. Cl. 8-111 20 Claims ABSTRACT OF THE DISCLOSUREParticulate compositons comprising admixtures of a water-solubleperoxymonosulfate and a water-soluble salt of a l to 4 carbon saturatedaliphatic monocarboxylic acid as an oxidation promoter; also, aqueouscompositions which are solutions of such a peroxymonosulfate having a pHof 5 to and containing the acylate anion of such an acid. Such solutionsare useful for oxidative purposes such as the bleaching of textileswhich are amenable to bleaching with peroxymonosulfate, and the removalof stains therefrom. The preferred peroxymonosulfate is the triple saltof potassium peroxymonosulfate of the formula KHSO -K SO -2KHSO Thepreferred promoters are the alkali metal acetates, e.g., sodium acetate.The preferred particulate compositions are substantially anhydrousadmixtures of the above potassium peroxymonosulfate, sodium acetate, abuffering agent such as trisodium phosphate or tetrasodiumpyrophosphate, and a solid desicating agent, preferably anhydrousmagnesium sulfate.

CROSS-REFERENCE TO RELATED CASE This application is acontinuation-in-part of my copending application Ser. No. 691,952, filedDec. 20, 1967 now abandoned.

BACKGROUND OF THE INVENTION Because of their well-known oxidativeproperties, many uses of peroxymonosulfuric acid and its salts(peroxymonosulfates) have been proposed in patents and chemicalliterature. Such uses include the shrink-proofing of wool, the bleachingof textiles, the removal of stains from textiles and solid surfaces, thecleaning of dentures, and the like. Peroxymonosulfuric acid and itssalts are also known to exert bacteriocidal activity.

Peroxymonosulfuric acid (H 50 is also sometimes called monopersulfuricacid or Caros acid; and its salts, i.e., the peroxymonosulfates, arealso sometimes called monopersulfates or caroates.

. While peroxymonosulfuric acid and its salts are useful for the aboveand other similar uses because of their oxidative properties, they arenot as effective as desired for such uses. The present invention isbased upon the discovery that certain readily available substancesactively promote the oxidative action of peroxymonosulfates and therebyenhance their effectiveness and usefulness for the above purposes.

SUMMARY OF THE INVENTION Particulate compositions comprising admixturesof a water-soluble peroxymonosulfate and from about 0.2 to 12 moles of awater-soluble salt of a 1 to 4 carbon saturated aliphatic monocarboxylicacid for each mole of the peroxymonosulfate.

Also, compositions which are aqueous solutions having a pH of about 5 to10 and containing the peroxymonosulfate ion (HSO and from about 0.2 to12 moles of the acylate ion of a l to 4 carbon saturated aliphaticmonocarboxylic acid per mole of the peroxymonosulfate ion.

Also, a method of bleaching textiles which are amenable to bleachingwith peroxymonosulfates, or of removing stains therefrom, comprisingsubjecting the textile to the action of such a solution.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS Any of the l to 4 carbonsaturated aliphatic monocarboxylic acids or their water-soluble saltswhich are free of heavy metal or other cations which would adverselyreact with or catalyze decomposition of the peroxymonosulfate aresuitable for use in accordance with the invention as the source of theacylate ion promoter of the oxidizing action of the peroxymonosulfate.Examples of suitable sources of acylate ions are formic, acetic,propionic and butyric acids; the alkali metal, ammonium, alkaline earthmetal, magnesium, cadmium and zinc salts of such acids; and mixtures oftwo or more of such acids and/or salts. Examples of unsuitable sourcesof acylate ions are the heavy metal salts of the above carboxylic acids,e.g., the iron, cobalt, copper, chromium and manganese salts, whichwould introduce heavy metal ions which tend to catalyze decomposition ofthe peroxymonosulfates. The preferred sources of acylate ion promotersare the carboxylic acids themselves and their ammonium and alkali metalsalts. The most preferred promoter is the acetate ion; and acetic acidand the ammonium and alkali metal acetates, particularly sodium andpotassium acetate, are the preferred sources thereof.

Any of the water-soluble salts of peroxymonosulfuric acid together witha water-soluble carboxylic acid salt of the type indicated above asbeing suitable sources of acylate ion promoters, may be used informulating the particulate compositions of the invention. Examples ofsuch peroxymonosulfates are the alkali metal, the alkaline earth metaland ammonium salts of peroxymonosulfuric acid and mixtures of any two ormore thereof. However, because of their superior stability, thepotassium salts such as potassium peroxymonosulfate monohydrate,

and the triple salt of potassium peroxymonosulfate of the formula 2HSO-K SO' -2KHSO are preferred for this purpose. The commercially availableform of this triple salt having an active oxygen content of about 4.7weight percent is the most preferred peroxymonosulfate for use. Forstability reasons, the particulate compositions should be essentiallydry, i.e., they should be essentially devoid of free water and of waterloosely held in the form of water of hydration. Preferably, allcomponents will be in their essentially anhydrous forms and the presenceof a desiccant material in particulate form to protect against thepresence of free water due to moisture picked up from the atmospherewill be desirable.

When formulating the solution compositions of the invention, any of theabove-mentioned peroxymonosulfates or peroxymonosulfuric acid itself maybe employed as the source of the peroxymonosulfate in, H Similarly, anyof the above-mentioned carboxylic acids, or the salts thereof previouslyindicated as being suitable, may be employed as the source of theacylate ion promoter. However, the aqueous solution containing bothperoxymonosulfate and acylate ions should have a pH in the range of 5 to10, since no significant promotional effect by the above acylate ionsupon the oxidizing action of the peroxymonosulfate ion has been observedto be exerted at higher or lower pH values. Solutions having a pH in therange 5.5 to 8 are preferred. Adjustment of the pH of the solution so asto bring it within the pH range of 5 to 10, preferably 5.5 to 8, may beaccomplished by the addition of any of the common soluble alkalinematerials, when an adjustment of the pH upward is necessary or desired;or by the addition of any of the common soluble acidic materials, whenan adjustment downward is necessary or desired. Suitable alkalinematerials for this purpose are the alkali metal and ammonium hydroxides,and alkaline reacting salts such as the alkali metal carbonates,phosphates and the like. Suitable acidic materials are nitric, sulfuric,phosphoric, and peroxymonosulfuric acids, and acid salts such as sodiumand potassium bisulfates.

In order to achieve significant promotion of the oxidizing action of theperoxymonosulfate ion, the mole ratio of acylate ion toperoxymonosulfate ion in the solution should generally be at least 0.211and a mole ratio of about 0.7 to :1 is preferred. Mole ratios of acylateion to peroxymonosulfate ion up to 12:1, or even higher, are alsoeifective and usable but generally are not attractive for cost reasons.Since the particulate compositions of the invention are especiallyuseful in formulating solutions meeting the above requirements, theparticulate compositions will generally be formulated by mixing theselected peroxymonosulfate and carboxylic acid salt in such proportionsas to satisfy the above acylate ion to peroxymonosulfate mole ratiorequirement.

The particulate compositions of the invention may be entirely free ofcomponents other than the peroxymonosulfate and carboxylic acid salt.However, they may also contain a source of alkali and/or a bufferingagent such as tetrasodium pyrophosphate in such an amount that when thecomposition is dissolved in water to give a 3% solution thereof, theresulting solution will have a pH within the desired range of 5 to 10.Still other materials such as stabilizers, wetting agents, fluorescentbrighteners and the like may also be incorporated, generally in minoramounts.

The particulate compositions of the invention containing bothperoxymonosulfate and carboxylic acid salt may be used as the source ofperoxymonosulfate in any of the various previously published uses ofperoxymonosulfates. Thus, such compositions may be used in formulatingdry bleaching compositions, e.g., for home laundry use, stain removalcompositions, and as a component in home laundry detergent formulationsand cleanser compositions. They may also be employed for sanitizing thewaters of swimming pools and as components of denture cleanercompositions.

A dry home laundry bleach composition can be formulated, e.g., with a 1:1 weight mixture of sodium acetate and the commercially availablepotassium peroxymonosulfate triple salt product. A bleaching compositioncontaining 50% of such a mixture with the balance consisting of lightgranular soda ash can be used effectively for home laundry bleachingpurposes when the composition is added to the laundry water to providean active oxygen concentration of about 20 to 50 p.p.m. Theincorporation of a alkyl aryl sulfonate, 35 to 50% of sodiumtripolyphosphate, 10% of sodium sulfate, and 10% of sodium metasilicate.The incorporation of small amounts of a soilrelease agent such as sodiumcarboxymethylcellulose and an optical brightener is generallyadvantageous.

Powdered cleanser compositions for removing stains from the surfaces ofporcelain, aluminum ware and stainless steel ware may also be formulatedusing a 1:1 mixture of sodium acetate and the potassiumperoxymonosulfate triple salt product. Such a cleanser composition maybe formulated using 5% of such a mixture, 5% of an alkyl aryl sulfonate,5% of anhydrous tetrasodium pyrophosphate, 5% sodium carbonate and 80%powdered small amount, e.g., 0.1%, of a fluorescent brightener isgenerally advantageous. Such a composition can also be added directly tothe washing water in washing machines to provide similar active oxygenconcentrations. The same composition can also be used for removing heavystains from clothing, particularly when added to hot tap water (l20-140F.) to provide active oxygen concentrations in the water of from about100 to 200 p.p.m. Such compositions are safe for use with Washablefabrics of all natural or synthetic fibers, with the possible exceptionof silk and wool which should be hand laundered at lower temperatures.They are also usable in the laundering of or the removal of stains fromwash-fast cloth fabrics dyed with common vat or sulfur dyes.

Mixtures of sodium acetate and the above potassium peroxymonosulfatetriple salt product, e.g., at a 1:1 weight ratio, are also usable informulating home laundry detergent compositions. Thus, such a detergentcomposition may contain 5% to 20% of such a mixture, 20% of an silica.Such compositions are generally applied to the damp surfaces from whichthe stains are to be removed, or they may be applied to a damp clothwhich is then rubbed over the stained surface to effect removal of thestain. Mixtures of a salt of a 1-4 carbon carboxylic acid such as sodiumacetate with the above-mentioned potassium peroxymonosulfate triple saltproduct, e.g., a 1:1 weight mixture, can be used directly to formsolutions for cleaning dentures. Alternatively, thesesolutions may alsocontain a synthetic detergent such as an alkyl aryl sulfonate, sodiumpyrophosphate and a flavoring agent. A dry denture cleaner compositionmay be formulated to contain about 50% of such a mixture, 15% anhydroussodium pyrophosphate, 1% of a synthetic detergent, 10% of trisodiumphosphate, 19% sodium sulfate and 5% sodium metasilicate. Such acomposition, when added to Water in an amount to provide from 50 to 250p.p.m. of active oxygen, provides a solution which is effective forcleaning dentures.

When the particulate composition of the invention is intended for use inpreparing solutions for bleaching textiles, it is preferred that itcontain a peroxymonosulfate and a salt of a 1 to 4 carbon saturatedaliphatic monocarboxylic acid together with a buifering agent in such anamount that when the composition is dissolved in water to give a bleachsolution having the desired active oxygen content, e.g., 0.002 to 0.4%and preferably 0.01 to 0.2%, the solution will also have the desired pH,e.g., 5 to 10 and preferably 5.5 to 8, without requiring the separateaddition of any pH adjusting agent. Buffering agents suitable for use informulating such compositions include sodium tripolyphosphate (Na P Osodium metasilicate (Na SiO sodium tetraborate (Na B O disodiumphosphate (Na HPO tetrasodium pyrophosphate (Na P O soda ash (Na CO andtrisodium phosphate (Na PO Of such agents, soda ash, tetrasodiumpyrophosphate (TSPP), trisodium phosphate (TSP) and disodium phosphate(DSP) are generally preferred. These preferred agents are highlyeffective and behave generally similarly, particularly in solutions forbleaching textiles, e.g., at temperatures from room temperature to 212F., preferably to F.

In formulating the particulate compositions containing buffering agents,the peroxymonosulfate, the salt of the carboxylic acid and the bufferingagent should be so proportioned that when the composition is dissolvedin water at a concentration to give a solution having the desired activeoxygen content, such solution will also have the desired pH and willcontain the salt of the carboxylic acid at a. concentration to providethe desired mole ratio of acylate ion to peroxymonosulfate ion. Asindicatedpreviously, the mole ratio of acylate ion:- peroxymonosulfateion may generally range from 0.2 to 12:1, or higher, the preferred moleratios being about 0.7 to 5 :1. When using sodium acetate as thecarboxylic acid salt component and the commercially available form ofthe triple salt of potassium peroxymonosulfate of the formula KHSO -K SO-2KHSO (active oxygen content of about 4.7% as the peroxymonosulfatecomponent, the weight ratios of sodium acetate: the triple salt willgenerally range from about 0.05 to 3.2:1, the

preferred range being 0.2 to 1.4:1. The amount of the buffering agent,e.g., soda ash, tetrasodium pyrophosphate (TSPP), trisodium phosphate(TSP), disodium phosphate (DSP), or mixtures thereof, in the particulatecomposition should be such that when a 3% aqueous solution of thecomposition is prepared, the solution will have a pH of to 10,preferably 5.5 to 8.

When the particulate composition of the invention is to be stored and/or shipped in bulk, it is preferred that a desiccant material inparticulate form be incorporated therein to guard against the adverseeffects of moisture that may be picked up from the atmosphere. Suitabledesiccant materials, i.e., desiccating agents, are anhydrous magnesiumsulfate, magnesium sulfate monohydrate anhydrous calcium sulfate,anhydros sodium sulfate, phosphorous pentoxide and lime. Of thesematerials, the anhydrous salts, particularly magnesium and calciumsulfate, are preferred with anhydrous magnesium sulfate being the mostpreferred. Any amount of such desiccating agent will generally bebeneficial in protecting against moisture pick-up, but amounts greaterthan about will seldom be used and usually will be undesirable becauseof their excessive diluting effect. The amounts most useful,particularly for the preferred desiccants are l to 4%, preferably 2.5 to3.5%, based upon the total composition weight. The desiccant material ismost effective when used in finely divided form. Preferably, thedesiccant will be in powder form with at least 90% thereof passingthrough a 100 mesh screen (US. Standard Sieve Series). Anhydrousmagnesium sulfate powder of that fineness has been used in preparingparticulate compositions in accordance with the invention containing, ona weight basis, 53.4 2% of the potassium peroxymonosulfate triple saltproduct, 35.6:

2% anhydrous sodium acetate, 8.1:0.5% trisodium phosphate (TSP), and2.91 0.5% magnesium sulfate. Such compositions exhibit good stabilityand protection against moisture pick-up. They will dissolve in water togive 3% solutions having a pH of 6.4102, and are generally useful forthe purposes disclosed herein.

An important use of the compositions of the invention is in thebleaching of textile fabrics containing portions dyed with a sensitivedyestuff. For such use, the bleaching solution containing theperoxymonosulfate and acetate is preferably buffered to a pH of 5.5 to8, e.g., using one of the buffering agents previously mentioned. Thebleaching can be effected at usual room temperatures, but temperaturesfrom 100 to 212 F. are preferred. At such temperatures, bleaching timesof from 10 minutes to 5 hours may be employed, the lower temperaturesgenerally requiring longer times than the higher temperatures. Bleachingmay be effected by immersing the fabric in the bleaching solutionmaintained at the desiredtemperature. Preferably, the fabric will beimpregnated or saturated with an amount of the bleaching solution equalto from about 50 to 150% of the fabric weight, and the saturated fabricwill then be heated to the desired temperature, e.g., by contacting itwith live steam or a mixture of steam and air, depending upon thetemperature desired. Most preferably, the bleaching is carried out usingequipment such as the well-known J-box which permits continuousoperation.

The following examples illustrate specifically the effectivness ofcompositions of the invention for removing stains from textile fabricsand for bleaching textile fabrics. In the examples and elsewhere in thespecification, all proportions expressed as parts or percentages are byweight.

EXAMPLE 1 A standard tea-coffee stained cotton fabric was prepared.The'whiteness value of the stained fabric was then determined using aHunter Reflectometer. In such a determination, the whiteness values arereported as percent reflectance representing the percent light reflectedfrom the sample as measured using the Hunter Reflectometer with a bluefilter for which magnesium oxide gives a reflectance of percent. Samplesof the stained fabric were then employed in home laundry bleachingtrials using a standard Launder-O-Meter. In one series of trials thelaundering liquid contained a commercial alkyl benzene sulfonate-basedlaundry detergent at a concentration of 0.1% with no other additive. Ina parallel series of trials the laundering liquid contained in additionto the 0.1% detergent an amount of the abovementioned commercialpotassium peroxymonosulfate triple salt product (active oxygen content4.7%) to provide 25 p. p.m. of active oxygen. In a third series oftrials the laundering liquid contained in addition to the detergent andthe potassium peroxymonosulfate product at the above concentrations,sodium formate, or sodium acetate, or sodium butyrate at a concentrationof 1.25 In each of the series or trials, the laundering operation wasrepeated 8 times for 10 minutes each at F. in the Launder-O-Meter,following which the fabric samples were washed and dried and thewhiteness values determined. The results are tabulated below. In thetabulation, the Points Gained Over Base represents the gains in pointsreflectance for the laundered fabric over the reflectance of theoriginal stained fabric (Base), whereas the Points Gained Over BaseDetergent represents the points in reflectance gained over thereflectance of the stained fabric after it had been laundered with onlythe detergent.

It will be seen from the above data that the addtion of either sodiumformate, sodium acetate, or sodium butyrate to the laundering liquidcontaining the peroxymonosulfate increased significantly the finalwhitness of the fabric. These salts clearly actively promoted thebleaching activity of the peroxymonosulfate. The promotional effect ofsodium acetate Was particularl outstanding in that the gain inreflectance points over the base plus the detergent was 6.7 as comparedwith only 3.9 when only the peroxymonosulfate was used with thedetergent. The increase of 2.8 points due, to the promotional effect ofthe sodium acetate represents an approximately 72% increase in whitenessover that obtained when the peroxymonosulfate was used alone with thedetergent.

EXAMPLE 2 Two strips of stained fabrics were made by sewing togetherpatches of heavily stained cotton fabric (obtained from Test Fabrics,Inc.) so that each test strip consisted of patches of variously' stainedfabrics together with patches of the same fabric which had previouslybeen bleached and patches which had not been bleached, i.e., the greyfabric. Each test strip was subjected to stain removal tests usingsolutions of the above-mentioned commercial potassium peroxymonosulfatetriple salt product with and without sodium acetate as a promoter.

The stain removal solutions contained 0.2% of the peroxymonosulfatetriple salt product and 0.4% sodium pyrophosphate decahydrate. One ofthe test solutions, Formula A, contained no sodium acetate, whereas theother solution, Formula B, contained 0.3% sodium acetate. The pH of eachsolution was 8.6 The test fabric strips were immersed in the solutionsat a liquortfabric weight ratio of 20:1 and the time of immersion was 3hours While the solutions were maintained at 140 F. The test strips werethen removed, rinsed thoroughly with water and dried.

The dried strips were then examined by three individuals and in allexaminations the individuals independently found that all of the stainsin the strip treated with Formula B were lighter than were thecorresponding stains in the strip treated with Formula A. Each patch ineach test strip was then placed over the aperture of a HunterReflectometer and backed with a standard having a reflectance of 83%,and the percent reflectance of each patch was then determined. Theresults are reported in the following tabulation.

Percent Reflectance It will be seen from the above results that stainremoval solution Formula B, containing sodium acetate, was substantiallymore effective than solution Formula A in removing the various stainsfrom the test strips.

EXAMPLE 3 A solution A was made up to contain 1.5% of the abovementionedcommercial potassium peroxymonosulfate triple salt product and 0.7%sodium pyrophosphate decahydrate. A similar Solution B was made upexcept that it also contained 1.6% sodium acetate trihydrate. The pH ofeach solution was 6.0. Samples of a caustic scoured 78 x 78, 4 yd./lb.cotton fabric were saturated with one or the other of the abovesolutions so as to contain 100% by weight of the solution, and thesaturated samples were then bleached in a saturated steam atmosphere at212 F. for minutes. After rinsing and drying, the whiteness of the clothsamples was determined. The percent reflectance of the sample treatedwith Solution A was 83.1%, whereas that of the sample treated withSolution B, containing sodium acetate, was 86.2%.

EXAMPLE 4 Samples of the same fabric used in Example 3 were treated asdescribed in Example 3 except that the treating solutions contained 2%(instead of 1.5%) of the potassium peroxymonosulfate triple salt productand each solution contained 3% sodium pyrophosphate decahydrate with1.5% sodium acid pyrophosphate being added to adjust the pH of allsolutions to 6.0. The bleaching results obtained using 4 such solutionscontaining 0, 1, 2 and 5% sodium acetate trihydrate are shown below.

Percent sodium acetate trihydrate: Percent reflectance O 86.4

EXAMPLE 5 umn B are those obtained using solutions containing sodiumacetate.

Two hundred grams of the commercial potassium peroxymonosulfate triplesalt product was dry-blended with an equal weight of anhydrous sodiumacetate for 20 minutes in a Twin Shell mixer. A bleaching solution wasprepared by dissolving 20 g. of the resulting mixture in 880 ml. ofwater, then adjusting the pH of the solution with a mixture of 35 ml. ofwater and 89 ml. of a 6% solution of tetrasodium pyrophosphatedecahydrate. A sample of caustic scoured 78 x 78 cotton fabric (4 yd./lb.) was saturated with the bleaching solution so as to contain 10% byweight of the solution, and the saturated sample was heated with steamat 190 F. for 20 minutes. The whiteness (percent reflectance) of thefabric sample was raised from 68.8 to 85.1 by the bleaching treatment.When another sample of the fabric was similarly bleached with thesolution at room temperature for 20 hours, the percent reflectance wasraised from 68.0 to 84.7.

EXAMPLE 7 I A particulate composition was prepared by dry-blending twoparts of anhydrous sodium acetate with three parts of the commercialpotassium peroxymonosulfate triple salt product in a Twin Shell mixer. A2.5% solution of the composition in water had a pH of 5.3. Portions ofthe resulting solution were then buttered by the addition thereto ofvarious buffering agents in the amounts indicated in the followingtabulation, whereby each of the resulting solutions had a pH of 6.4-6.5.The resulting solutions were used to bleach IO-gram samples of a causticscoured cotton print cloth having an unbleached whiteness (percentreflectance) of 67.7. The bleaching was effected by saturating the clothwith an equal weight of the bleaching solution and then heating thesaturated cloth at F. for 1 hour. After the bleaching treatment, thefabric was rinsed with 500 ml. of water, the pH of the rinse water andthe percentage of residual active oxygen therein were determined and thewhiteness of the bleached fabric was measured. The results, togetherwith the amounts of buffering agents employed, are shown in thefollowing tabulation.

In the following tabulations, TSP stands for trisodium phosphate, DSPstands for disodium phosphate and TSPP stands for tetrasodiumpyrophosphate.

pH of Percent Percent cloth residual in rinse active Percent TestIdentity Butler solution water oxygen reflectance A Anhydrous TSP 0. 265. 5 40 88. 1 B Anhydrous DSP 0.50 5. 45 35 87. 8 C. Anhydrous sodiummetasilicate 0. 14 5. 35 52 87. 5 D Borax pentahydrate 0. 33 5. 3 47 8G.8 E Anhydrous TSPP powder 0. 47 5. 6 48 88. 0

EXAMPLE 8 sodium pyrophosphate powder (TSPP) and 1.85 parts of anhydroussoda ash in place of the 2.25 parts of TSP. Compositions A, B and C wereeach dissolved in about 970 parts of water togive bleach solutionshaving a pH of 6.4 and containing 1.5% of the above triple salt product.

The resulting solutions were used to bleach samples of a caustic scouredcotton print cloth having starting whitenesses (percent reflectance) of68.068.7%. Bleaching was effected ,by saturating the cloth sample withan equal weight of the bleach solution, then heating the saturatedsample at 160 F. The bleaching times at 160 F., the percentages ofresidual or unused active oxygen at the end of the bleaching times andthe bleach results are shown in the following tabulation.

Bleaching Residual When the above bleaching procedure is repeated usinga composition composed of 54.7% of the triple salt product, 27.2% sodiumacetate and 18.1% disodium phosphate in place of composition A,essentially the same results are obtained as those reported above forcomposition A.

EXAMPLE 9 Five samples of various colored fabrics, each about 6 ft. x 10in., are butt-seamed together and the resulting assembly is butt-seamedinto the center of a 100 yd. x 10 in. sample of unbleached cotton fabricto form a fabric train. The colored samples are: (a) an all-cottonfabric containing a /2-in. check pattern dyed with a blue copperphthalocyanine dye; (b) a 50:50 cotton/polyester fabric having a /2-in.check pattern containing disperse and naphthol red dyes; (c) anall-cotton light-weight fabric having a l-in. check. pattern dyed with anaphthol red dye; (d) a medium-weight all-cotton fabric having naphtholred stripes and yellow stripes against a white background; and (e) anall-cotton seersucker containing alternating Ms-in. white and greenstripes dyed with a vat green dye. The fabric train is continuouslysaturated with an equal weight of a bleaching solution which is a 2.8%solution of a particulate composition containing 8.3% anhydroustrisodium phosphate, 36.7% anhydrous sodium acetate and 55% of thecommercial potassium peroxymonosulfate triple salt product, the :pH ofthe solution being 6.4. The saturated fabric is passed continuouslythrough a I-box maintained at about 185 F. with a mixture of steam andair, the rate of travel through the J-box being such as to give aresidence time therein for the fabric of about 1 hour. The bleachedfabric is withdrawn from the J-box and after being washed in hot water,all the colored fabric samples, in the train are found to be wellbleached with no evidence of bleeding or mark-01f of the dyes ontoundyed portions of the fabric.

When the above procedure is repeated using bleach solutions preparedfrom similar particulate compositions containing anhydrous soda ash,anhydrous tetrasodium pyrophosphate or anhydrous disodium phosphate inplace of trisodium phosphate, generally similar results are obtained.Such bleach solutions are also effective in bleaching alkali sensitivefabrics such as those containing cellulose triacetate fibers.

The above examples demonstrate the effectiveness of sodium formate,sodium acetate and sodium butyrate in promoting the oxidative action ofpotassium peroxymonosulfate in removing stains from textiles and inbleaching textiles. Similar results are obtainable using other salts ofthe 1 to 4 carbon saturated aliphatic monocarboxylic acids, or the acidsthemselves, in place of the sodium formate, sodium acetate, or sodiumbutyrate shown. Similarly, corresponding results are obtainable usingother water-soluble peroxymonosulfates, such as the sodium and ammoniumperoxymonosulfates, in place of the potassium peroxymonosulfate triplesalt product used in the examples. The effectiveness of such acylatecompounds in promoting the oxidative action of peroxymonosulfates wasentirely unexpected and obviously is highly advantageous and practical.

The promoting effect of ac'ylates of the above type on the oxidativeaction of peroxymonosulfates can be realized under any of the conditionsthat peroxymonosulfates are known to be active, e.g., in bleaching orstain removal operations. Thus, the compositions of the invention can beemployed in bleaching or stain removal operations at ordinary orelevated temperatures, in immersion-type bleaching operations or inoperations where the fabric to be bleached is simply saturated with 50to 150%, preferably to of the bleach solution containing theperoxymonosulfate and the promoter and then permitted to bleach in thesaturated state at either room or higher temperatures, e.g., steamingtemperatures.

I claim:

1. A particulate composition consisting essentially of an admixture of awater-soluble peroxymonosulfate and a water-soluble salt of a carboxylicacid from the group consisting of formic, acetic, propionic and butyricacids, which salt is free of cations which would adversely react with orcatalyze the decomposition of said peroxymonosulfate, said compositioncontaining from 0.2 to 12 moles of said per mole of saidperoxymonosulfate.

2. A composition according to claim 1 wherein the peroxymonosulfate is apotassium peroxymonosulfate and the salt of the carboxylic acid is anacetate.

3. A composition according to claim 1 wherein the peroxymonosulfate is apotassium peroxymonosulfate triple salt of the formula KHSO -K SO -2KHSOand the salt of the carboxylic acid is an acetate.

4. A composition according to claim 1 wherein the peroxymonosulfate is apotassium peroxymonosulfate and the salt of the carboxylic acid issodium acetate, which composition also contains a buffering agenteffective to buffer a 3% aqueous solution of the composition containing0.002 to 0.4% active oxygen derived from said peroxymonosulfate at a pHin the range 5 to 10.

5. A composition according to claim 3 wherein the acetate is sodiumacetate.

6. A composition according to claim 4 wherein the peroxymonosulfate is apotassium peroxymonosulfate triple salt of the formula KHSO -K SO -2KHSOand the buffering agent is from the group consisting of sodiumtripolyphosphate, sodium metasilicate, sodium tetraborate, disodiumphosphate, soda ash, tetrasodium pyrophosphate and trisodium phosphate.

7. A composition according to claim 6 wherein the weight ratio of sodiumacetate:said triple salt is from 0.05 to 3.2: 1, which compositioncontains soda ash in an amount such that a 3% aqueous solution of thecomposition will have a pH of 5 to 10.

8. A composition according to claim 6 wherein the weight ratio of sodiumacetate:said triple salt is from 0.05 to 3.211, which compositioncontains tetrasodium pyrophosphate in an amount such that a 3% aqueoussolution of the composition will have a pH of 5 to 10.

9. A composition according to claim 6 wherein the weight ratio of sodiumacetate:said triple salt is from 0.05 to 3.2: 1, which compositioncontains trisodium phosphate in an amount such that a 3% aqueoussolution of the composition will have a pH of 5 to 10.

10. A composition according to claim 6 wherein the weight ratio ofsodium acetate:said triple salt is from 0.05 to 3.2: 1, whichcomposition contains disodium phosphate in an amount such that a 3%solution of the composition Will have a pH of 5 to 10.

11. A composition according to claim 6 which also contains a desiccatingagent in an amount up to of the composition weight.

'12. A composition according to olaim 6 which also contains 1 to 4%,based on the composition weight, of a. finely divided desiccating agentwhich is anhydrous magnesium sulfate or anhydrous calcium sulfate.

13. A composition according to claim 9 consisting essentially of about55 weight percent of said triple salt, about 36.7 weight percent ofsodium acetate and about 8.3 weight percent of trisodium phosphate.

14. A composition according to claim 10 consisting essentially of about54.7 Weight percent of said triple salt, about 27.2 weight percent ofsodium acetate and about 18.1 weight percent disodium phosphate.

15. A composition according to claim 12 wherein the weight ratio ofsodium acetatezsaid triple salt is from 0.05 to 3.2:1, the buffer istrisodium phosphate and the desiccating agent is anhydrous magnesiumsulfate.

16. A composition according to claim 15 containing, on a weight basis,about 51.4 to 55.4% of said triple salt, 33.6 to 37.6% anhydrous sodiumacetate, 7.6 to 8.6% trisodium phosphate and 2.4 to 3.4% anhydrousmagnesium sulfate, which composition will dissolve in water to give a 3%solution having a pH of from 6.2 to 6.6.

17. A composition according to claim '16 which contains about 53.4% ofsaid triple salt, about 35.6% an- 12 hydrous sodium acetate, about 8.1%trisodium phosphate and about 2.9% anhydrous magnesium sulfate.

18. A composition comprising an aqueous solution having a pH of 5 to 10and consisting essentially of the peroxymonosulfate ion and from 0.2 to12 moles of the acylate ion of an acid from the group consisting offormic, acetic, propionic and butyric acids, for each mole ofperoxymonosulfate ion present in said solution.

19. A composition according to claim 18 in which the acylate ion is theacetate ion, which solution contains a buffer from the group consistingof sodium tripolyphosphate, sodium metasilicate, sodium tetraborate,disodium phosphate, soda ash, tetrasodium pyrophosphate and trisodiumphosphate.

20. A composition according to claim 19 which has a pH of 5.5 to 8.

References Cited UNITED STATES PATENTS 2,996,350 8/1961 Taylor 252186X3,048,546 8/1962 Lake et a1. 252 3,130,165 4/1964 Brocklehurst 252-99MAYER WEINBLATT, Primary Examiner US. Cl. X.R. 252-95, 99, 186

